RPMs in relation to MPH

Question
Hello.........thanks for taking the time to help us out.
My husband and I have a 1995 Sea Ray V-6 4.3 Mercruiser.  The boat has 260 hours on it and it is 18.5' long.  The last two times we had her out at a speed of 35 mph the rpm's were at 50.  Is this a problem?  We don't know what they should be at what speeds.  We just bought the boat this summer.  If this is a problem do you know what we need to do to correct it?  Thanks.  Kathy

Answer
Hi Kathy...Thank you for selecting the undersigned to reply to your question.

I'm not a mechanic, however, you definitely have a problem with 35mph producing 5000rpm. I could involve a modified/low gear ratio or the pitch and diameter of the prop. Best you consult a qualified and reliable marine mechanic to resolve, and in the meantime, check your Mercury owners manual.

Safe Boating
Ron